In quicpacketcreator::createandserializestreamframe, set packet_buffer.buffer to nullptr before function returns. no behavior change, not protected.
In quicpacketcreator::createandserializestreamframe, set packet_buffer.buffer to nullptr before function returns. no behavior change, not protected.

This is similar to cl/320427430.

PiperOrigin-RevId: 320949846
Change-Id: Iddb12031ddfaed8ed2281f5a2c3433700c625b07

google/quiche,google/quiche,google/quiche,google/quiche